Relievable check valve for medical lines

ABSTRACT

This invention concerns relievable normally closed check valves for use in conjunction with fluid delivery systems for medical patients, as well as methods for making and using valves. In the medical context, such valves function at very low fluid pressures, and include a multi-part valve body made from upper and lower housings capable of movement relative to each other that, when operably connected, dispose between them a compliant or deformable, resilient valve element normally biased in the closed position against a valve seat present on the inner surface of the upper housing. The upper housing also includes a lower housing seat. The inside surface of the lower housing contains or supports a structure that positions the valve element to engage the valve seat in the absence of fluid pressure above the valve&#39;s pre-determined cracking pressure. The valve&#39;s flow prevention function may be relieved in the absence of sufficiently pressurized fluid by causing the valve element to disengage from the valve seat, for example, by adjusting the valve body to distance the valve element from the valve seat.

RELATED APPLICATION

This application claims the benefit of and priority to now allowed, U.S.patent application Ser. No. 14/057,246 (attorney docket no.IVO-0002-UT), filed on 18 Oct. 2013, which claims priority to expiredU.S. provisional patent application Ser. No. 61/715,759 (attorney docketno. IVO-0002-PV), filed on 18 Oct. 2012, the contents of which areherein incorporated by reference in its entirety for any and allpurposes.

GOVERNMENT SUPPORT

None.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates generally to relievable, normally closed one-waycheck valves that permit pressurized fluid flow in only one directionwhen the fluid is pressurized at or above the valve's cracking pressure,and particularly to valves suitable for use with intravenous cathetersand medical lines.

2. Shortcomings of Existing Solutions

A common shortcoming with conventional, normally closed one-way medicalcheck valves is the inability to rapidly and easily bypass the valve incertain circumstances where the valve is closed and thus prevents fluidfrom flowing though the valve, for example, when a peristaltic pumpfails. To overcome such circumstances in clinical settings today,medical technicians must either exert manual pressure on a fluidreservoir (e.g., an I.V. bag) upstream of the valve in order to overcomethe particular check valve's cracking pressure, position the fluidreservoir at a height above the check valve sufficient to create headpressure in the system sufficient to overcome the particular valve'scracking pressure, or, as is often the case, remove the check valve fromthe series of connectors and tubes that connect the fluid reservoir tothe patient's vasculature. Having to exert manual pressure on orrepositioning a fluid reservoir is clearly disfavored as veryinefficient. Removal of the check valve is not only inefficient, it isalso dangerous, as doing so increases the risk of making improperconnections (which, in turn, can lead to medical mistakes, e.g.,administration of the wrong or too much drug, etc.), and may alsodisrupt or destabilize a catheter access or insertion point. Thus, thereis a clear need for improved check valves and related methods.

Definitions

Before summarizing or describing the instant invention in detail,several terms used in the context of the invention will be defined. Inaddition to these terms, others are defined elsewhere in thespecification, as necessary. Unless otherwise expressly defined herein,terms of art used in this specification will have their art-recognizedmeanings.

A “check valve” refers to a mechanical valve that normally allows fluidto flow through it in only one direction, from the upstream directiontoward the downstream direction, thereby preventing, or “checking”,fluid flow in the other direction. Check valves have at least one fluidinlet port and at least one fluid outlet port. A common type of checkvalve is a diaphragm check valve, which typically uses a flexing orresilient diaphragm, a spring-loaded ball, or the like in the valve bodypositioned to create a normally-closed valve. Pressure on the upstreamside of the valve element must be greater than the pressure on thedownstream side by a certain amount, known as the “cracking pressure” or“pressure differential”, for the valve element of the check valve toopen and thereby allow fluid flow through the valve, from the inletport(s) through the valve body and exiting via the outlet port(s). Iffluid pressure drops below the valve element's cracking pressure, thevalve element automatically returns to its original, closed positionagainst its corresponding valve seat.

A check valve's “cracking pressure” refers to the minimum rated pressuredifferential required to cause the valve to open and permit fluid flow.A relievable check valve according to the invention will be designed toat operate at a specific, pre-determined cracking pressure (i.e., the“rated” cracking pressure). Preferred cracking pressures for relievablemedical check valves according to the invention range from about 0.01 toabout 4 pounds per square inch (psi). Particularly preferred crackingpressures include about 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08,0.09, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 2, 3, and 4 psi.While this specification focuses on relievable medical check valves,those in the art will appreciate that the instant invention will alsoapply in the context of check valves designed to operate at much higherfluid pressures, cracking pressures, and with different fluids(including oils, gases, slurries, etc.).

A cracking pressure may be termed to be “pre-determined” or “preset”,which means that the cracking pressure is known, either by testing todetermine cracking pressure or by calculations that consider suchfactors as the materials used to build the valve, the sizes, shapes andgeometries of the various components, etc.

A “normally closed” check valve refers to one that substantiallyinhibits, and optimally prevents, fluid flow through the valve. Whilesome leakage around a valve element may be permissible in a givencontext, preferred valves according to the invention are those that donot leak when closed.

Mechanical components that are “operably connected” means that thecomponents are connected in manner to accomplish the desired function.For example, in the context of the invention, upper and lower housingsare “operably connected” when they are joined (or otherwise fittedtogether) to form a functional valve body of a check valve of theinvention, which valve body in many embodiments allows for relativemovement of the lower or upper housing in relation to the upper or lowerhousing, as the case may be, without appreciable leakage, and preferablyno leakage, of fluid from inside the valve body from the connection(threaded, pressure fit, or otherwise) between the upper and lowerhousings. In the preceding sentence, a “functional” valve body refersonly to a valve body that provides for fluid ingress through one or moreinlet ports located on the upper housing and fluid egress from one ormore outlet ports located on the lower housing. In contrast, a“functional” relievable check valve according to the invention is onethat provides for cessation of flow when fluid in the system lackssufficient pressure to overcome the valve's cracking pressure unless anduntil a medical technician or other user adjusts the valve so as tocause the valve element to disengage from the valve seat and therebyallow fluid having a pressure below the valve's cracking pressure toflow through the valve. In preferred embodiments, even when the valve'sfluid-checking functionality is interrupted or relieved, the valve stillonly permits one-way flow through the valve.

A “patentable” composition, process, machine, or article of manufactureaccording to the invention means that the subject matter satisfies allstatutory requirements for patentability at the time the analysis isperformed. For example, with regard to novelty, non-obviousness, or thelike, if later investigation reveals that one or more claims encompassone or more embodiments that would negate novelty, non-obviousness,etc., the claim(s), being limited by definition to “patentable”embodiments, specifically exclude the non-patentable embodiment(s).Also, the claims appended hereto are to be interpreted both to providethe broadest reasonable scope, as well as to preserve their validity.Furthermore, the claims are to be interpreted in a way that (1)preserves their validity and (2) provides the broadest reasonableinterpretation under the circumstances, if one or more of the statutoryrequirements for patentability are amended or if the standards changefor assessing whether a particular statutory requirement forpatentability is satisfied from the time this application is filed orissues as a patent to a time the validity of one or more of the appendedclaims is again considered.

A “plurality” means more than one.

A “relievable” normally closed check valve refers to one that inhibitsor prevents flow when fluid in the system lacks sufficient pressure toovercome the valve's cracking pressure unless and until a technician(e.g., a doctor, medical technician, nurse, paramedic, etc.) or otheruser adjusts the valve so as to allow fluid flow through the valve. Suchrelief may be reversible or permanent, depending upon the design of theparticular valve.

SUMMARY OF THE INVENTION

The object of this invention is to provide inexpensive, patentable,improved normally closed one-way check valves that allow theflow-prevention feature(s) such valves to be easily and rapidly relievedby a technician or other user when flow pressures are below theparticular valve's rated cracking pressure. Valve closure can berelieved in any suitable way, including, for example, by (i) having atechnician change, via adjustment initiated or performed by thetechnician, the physical relationship between various components in thevalve, (ii) applying a pressure other than fluid pressure to create asufficient pressure differential between the inlet and outlet sides ofthe valve element to cause the valve to open and permit fluid flow, or(iii) providing a second flow path that bypasses the parts of the valvethat provide the check valve functionality.

Thus, one aspect of the invention provides simple yet reliablerelievable, normally closed one-way check valves in which valve closurein the absence of a sufficient pressure differential to cause valveopening is achieved by changing the physical relationship betweenvarious valve components. Changing the physical relationship betweenvarious valve components is typically accomplished by a user (e.g.,doctor, medical technician, nurse, etc.) making an adjustment to one ormore components of the valve.

In general, such valves comprise only a few components and, in themedical context, such valves typically are also designed to function atvery low fluid pressures. Such relievable check valves comprise a valvebody made from joined upper and lower housings capable of movement inrelation to each other in use. The valve body includes a fluid inlet, afluid outlet, a valve seat and a lower housing seat each disposed in theupper housing, and a deformable, resilient valve element that ispositively biased to close against the valve seat in the absence of apre-determined fluid pressure differential across the valve element. Theupper and lower housings can be moved in relation to one another so asto disengage the valve element from the valve seat. Any suitablestructure, or combination of structures, that provides suchfunctionality, is within the scope of invention.

Another aspect of the invention concerns relievable one-way check valvesthat provide the capability for a user to manually disengage the valveelement from the valve seat. Any suitable structure, or combination ofstructures, that provides such disengagement of the valve element fromthe valve seat is within the scope of the invention. A representativeexample involves the use magnetic repulsion. Another exemplaryconfiguration allows movement of a mechanical support structure for thevalve element in relation to the lower housing, which movementdisengages the valve element from the valve seat.

Yet another aspect of the invention concerns relievable one-way checkvalves having a secondary fluid flow path that allows the primary fluidpath, which contains a check valve, to be bypassed when desired.

Together with other objects and advantages, which will becomesubsequently apparent reside in the details of construction andoperation as more fully hereinafter described and claimed, referencebeing had to the accompanying drawings forming a part hereof, whereinlike numerals refer to like parts throughout.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is an exploded perspective view of the present invention readyfor assembly.

FIG. 2 is a cross-sectional side view of an assembled embodiment of adevice according to the invention, which embodiment is shown in anexploded cross-sectional side view in FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION

1. Overview

This invention relates to relievable one-way check valves for use inconjunction with fluid delivery systems, particularly systems fordelivering fluids and/or medicines to patients undergoing treatment, aswell as methods for making and using such relievable check valves. Inmedicine, such valves function at very low fluid pressures, and inhibitor prevent fluid flow through the valve absent fluid pressure at orabove the valve's cracking pressure. That said, as those in the art willappreciate, the invention also envisions much larger relievable one-waycheck valves, designed to operate at much higher pressures, within itsscope.

2. Detailed Description

The object of this invention is to provide inexpensive, patentable,improved normally closed one-way check valves that allow theflow-prevention feature(s) of such valves to be easily and rapidlyrelieved at flow pressures below the particular valve's crackingpressure. Valve closure can be relieved in any suitable way, including,for example, by changing the physical relationship between variouscomponents in the valve, by applying a pressure other than fluidpressure to create a sufficient pressure differential between the inletand outlet sides of the valve element to cause the valve to open andpermit fluid flow, or by providing a second flow path that bypasses theparts of the valve that provide the check valve functionality.

As described below, a relievable one-way check valve of the inventionincludes a multi-part valve body made from a plurality of housingmembers. In many preferred embodiments of low-pressure one-way medicalcheck valves according to the invention, the valve body comprises twohousing members, a “first” or “upper” housing and a “second” or “lower”housing, designed and manufactured to be operably connected to eachother to form the valve body, in many embodiments in a manner thatallows for relative movement between the housing members. A valveelement is disposed within the valve body, and is positioned by anysuitable structure(s) to normally be biased in the closed positionagainst a valve seat in the absence of fluid pressure above the valve'spre-determined cracking pressure. The valve's normally closed positioncan be relieved by a technician (e.g., a doctor, medical technician,nurse, paramedic, etc.) or other user who adjusts the valve so as toallow fluid flow through the valve. Valve closure can be relieved in anysuitable way, including, for example, by changing the physicalrelationship between various components in the valve, by applying apressure other than fluid pressure to create a sufficient pressuredifferential between the inlet and outlet sides of the valve element tocause the valve to open and permit fluid flow, or by providing a secondflow path that bypasses the parts of the valve that provide the checkvalve functionality.

A number of non-limiting, representative preferred embodiments of theinvention are described in greater detail below.

A. Relievable Check Valves Having Adjustable Valve Bodies

One aspect of the invention provides simple yet reliable relievable,normally closed one-way check valves in which valve closure in theabsence of a sufficient pressure differential to cause valve opening isachieved changing the physical relationship between various valvecomponents. In general, such valves comprise only a few components and,in the medical context, such valves typically are also designed tofunction at very low fluid pressures.

Such relievable one-way check valves comprise an adjustable valve bodymade from joined upper and lower housings capable of being moved inrelation to each other. The valve body includes a fluid inlet, a fluidoutlet, a valve seat and a lower housing seat each disposed in the upperhousing, and a deformable, resilient valve element that is positivelybiased to close against the valve seat in the absence of apre-determined fluid pressure differential across the valve element. Theupper and lower housings can be moved in relation to one another so asto disengage the valve element from the valve seat. Any suitablestructure, or combination of structures, that provides suchfunctionality, is within the scope of invention.

Preferred materials for the deformable, resilient valve element includenatural or synthetic elastomeric, or rubber-like materials that cancompress, deflect, or bend above a pre-determined pressure threshold. Insome preferred embodiments, the valve element comprises two components,a first disk comprised of a natural or synthetic flexible, resilientmaterial (or flexible combination of natural or synthetic materials) anda second disk comprised of a semi rigid, resilient material (orcombination of materials) that provides support to and preventsdistortion of the first disc while also providing the capacity to deformwhen fluid pressures above the valve's pre-determined cracking pressureare experienced.

In some preferred embodiments, such a configuration is accomplishedusing a mechanical support structure having a linearly arrayed pluralityof spaced valve element posts. In some of these embodiments, thedeformable, resilient valve element positioned within the valve bodyprior to assembly of the upper and lower housings has a flexible,compliant multi-layer construction, wherein the first disk (whichcontacts the valve seat) is preferably made from pure gum rubber and/orlike material and the second, supporting disk is made from a semi-rigidplastic material, such as unplasticized polyvinyl chloride (PVC).Because of the flexible, resilient nature of such a dual diskconstruction, the disk structure can open under a very low pressure,such as 0.02 pounds per square inch. Opening occurs by bending ordeflection of the valve element about a bending axis defined by thelinearly arrayed plurality of spaced valve element posts.

In other embodiments, a central support structure comprised of one ormore support elements contacts a central support region on the lowerportion of the valve element, allowing the valve element to deflectabout its periphery to disengage from the valve seat and allow fluidflow when fluid flows into the valve body at a pressure above thepre-determined cracking pressure for the particular valve. In suchembodiments, the support structure(s) constantly hold the valve elementbiased in position against the valve seat unless and until fluid havinga pressure above the cracking pressure moves into the valve body.

In preferred embodiments that employ a disk-type valve element, thevalve element preferably has an edge profile that minimizes gas bubbleformation about its periphery. Preferred edge profiles include a stepprofile, wherein the upper portion of the valve element (e.g., the firstdisk), the surface of which engages the valve seat, has, for example, alarger diameter than the lower portion of the valve element (e.g., thesecond disk). Preferably, the first and second disks are concentricallystacked (and preferably permanently attached) during assembly.

In other embodiments, the valve element comprises a ball to which aseating force is applied by biasing member such as a spring or elastic,compressible component bearing against and holding the ball in placeagainst the valve (or, in these embodiments, ball) seat of the upperhousing. The valve element may be supported by a support structureformed as part of, or, alternatively, placed within, the lower housing.After the various components are assembled into a valve body, thebiasing member forces the ball against the valve seat, biasing the valvein a normally closed position. In normal operation, fluid flow throughthe valve becomes possible when the pressure of the fluid flowing intothe valve meets or exceeds the valve's pre-determined cracking pressure.If the inlet pressure is reduced such that the pressure differentialrequired to open the valve element is no longer present, the biasingmember of the valve element causes the ball to again engage the valveseat, arresting fluid flow through the valve. If desired, flow throughthe valve of a fluid that exerts a pressure differential across thevalve element that is less than that of the valve's cracking pressurecan be achieved by relieving the closure of the valve element againstthe valve seat. This can be accomplished by any suitable structure, orcombination of structures, for example, by moving the lower housing inrelation to the upper housing so that structures inside the valve bodymove apart, allowing the valve element to disengage from the valve seatand thereby permit fluid flow.

Thus, in preferred embodiments, easy, rapid relief of one-way checkvalve functionality is provided by allowing a technician to move thelower and upper housings in relation to one another such that the valveelement no longer contacts the valve seat, allowing fluid to flowthrough the valve without regard to inlet pressure. Any suitableconfiguration that provides for such relative movement of the lower andupper housings so as to allow the valve element to disengage the valveseat in the absence of fluid flow at or above the check valve'spre-determined cracking pressure can be employed. One such preferredconfiguration employs threaded lower and upper housings. Suchconfigurations allow the lower housing to be partially disengaged fromthe upper housing (e.g., by partially unscrewing the lower housing fromthe upper housing), thereby allowing the valve element to disengage fromthe valve seat. To restore check valve function, the lower housing canbe moved to again fully engage the upper housing, which causes the valveelement to again engage the valve seat and thus close the check valve(provided that fluid at or above the cracking pressure is not thenflowing through the valve).

If back-flow prevention is desired in a relievable one-way check valveaccording to the invention, structural provision can be made to allowthe valve element to become reseated against the valve seat in the eventof back flow. In such embodiments, fluid flow reversal causes the valveelement to re-engage the valve seat, thereby preventing back flow. Insome embodiments of this type, the valve element may have sufficientbuoyancy in the absence of fluid flow to float to and re-engage thevalve seat when the valve body is oriented in a way that allows suchmovement.

Representative Example:

FIG. 1 illustrates, in exploded perspective, a particularly preferredembodiment of a relievable one-way check valve according to theinvention. As shown, the valve (1) comprises a multi-part valve body(10) made by joining an upper housing (20) to a lower housing (40). Theupper housing (20) has a top surface flange (21) having a dependingcircumferential axially extending wall flange (22) integral therewith. Afluid inlet (24) projects upward from the central region of the topsurface flange (21) and has a central bore (25) that extends from theinlet port (26) to an interior opening (27) in the interior (28) of theupper housing (20). The central bore (25) may have any desired shape. Inthe depicted embodiment, the central bore has a tapering cylindricalconfiguration. In order to operably connect with the lower housing (40),the interior surface (29) of the wall flange (21) of the upper housingincludes female threads (23) therein.

The lower housing (40) has a bottom surface flange (41) whose interior(42) is shaped to form an upwardly expanding cone portion (43). Integralwith the upper circumference of the cone portion (43) is a peripheralaxially extending flange (44). A fluid outlet in the form of a taperedLuer connector (45) projects downward from the central region of bottomsurface flange (41) and has a central bore (46) that extends from theoutlet port (47) to an interior opening (48) in the interior (42) of thelower housing (40). If desired, one or more ribs (not) shown may beprovided on the inner surface (49) of the extending flange (44). Theexterior surface (50) formed by the circumferential exterior faces ofbottom surface flange and the axially extending flange (44) includesmale threads (51) that match the female threads (23) of the upperhousing, allowing the upper and lower housing (20, 40) to be screwedtogether to form the valve body. Those in the art will also appreciatethat in variations of this embodiment, a seal (30) and/or sealing flangeneed not be present, particularly when the manually adjustableconnection between the upper and lower housings (20, 40) itself affordsa sufficiently watertight seal for the intended application.

When operably connected, by screwing or otherwise fastening together theupper an lower housings (20, 40), the upper edge of the peripheralaxially extending flange (44) has a sealing flange (54) configured tomake a sealing connection with a seal (30) positioned at or near theperiphery of the interior surface (32) of the top surface flange (21).As with other components of relievable check valves of the inventionintended for medical applications, the seal (30) is made from anysuitable biocompatible, compressible material. In preferred embodiments,operable connection of lower and upper housings (40, 20) compresses theseal (30), ensuring a watertight connection between the components usedto form the valve body (10).

If desired, ribs (or similar structures) may be used to help retain thevalve element (60) in its central position within the valve body (10)after assembly of the upper and lower housing elements (20, 40). Ribs(or the like), if present, can, for example, be positioned around theinner circumference (52) of the axially extending flange (44) of thelower housing (40).

In this embodiment, the valve element (60) is of the dual-disk variety.It comprises a first, upper disk (61) made of rubber or a rubber-likematerial (e.g., silicone) bonded concentrically to a second, lower disk(62) made of a semi-rigid plastic material, preferably an unplasticizedplastic, for example, an unplasticized PVC film. In the particularembodiment depicted in FIG. 1, the second disk (62) has a slightlysmaller diameter than the upper disk (61).

A representative example of a suitable upper disk is one having thefollowing characteristics. The material is tan pure gum floating naturalrubber flat sheet stock having a durometer of 40±5 Shore A, a thicknessof 0.031 inches (about 0.8 mm), a specific gravity of 0.92, tensilestrength of about 2,500 psi (about 0.175 kg/cm²), and an elongation ofat least about 650%. Circular disks having a diameter of 0.375 inches(about 9.5 mm) can be cut from the flat sheet stock using a die. Anotherrepresentative example of a suitable upper disk is a silicone elastomer(e.g., SILASTIC®, Dow Corning Corp.) having the followingcharacteristics: a durometer of 40-50, a specific gravity of about 1.15,a tensile strength of about 1,000 psi (about 0.07 kg/cm²), and anelongation of at least about 650%. A representative example of asuitable lower disk is one having a diameter of 0.350 inches (about 8.9mm) die cut from unplasticized PVC flat sheet film stock having athickness of 0.007-0.0075 inches (about 0.18-0.19 mm), a specificgravity of 1.3, tensile strength of 5,700 psi (about 0.4 kg/cm²),elongation of 125%, and a Rockwell Hardness of R98-106.

Returning to FIG. 1, the valve element (60) is positioned on linearlyarrayed, spaced support posts (53) extending from the face of theupwardly expanding cone portion (43) of the bottom surface flange (41)of the lower housing (40). After assembly into a valve body, the spacedsupport posts (53) firmly and positively bias the valve element (60)into engagement with the valve seat (31) disposed on the interiorsurface (32) of the top surface flange (21).

In operation, the normal position of the valve element (60) is that ofsealing engagement with the valve seat (31), preventing fluid flowthrough the valve unless or until the valve's cracking pressure is metor exceeded. In the embodiment depicted in FIG. 1, when a technician orother user wishes to relieve the valve's valving function (i.e., controlof fluid flow by opening or closing a valve), s/he moves the lower andupper housings (40, 20) relative to one another by partially unscrewingthe housings, thereby causing the surface of the expanding cone portion(43) to move away from the interior surface (32) of the top surfaceflange (21), which in turn causes the valve element (60) to move awayfrom the valve seat (31). Provided there is sufficient relative movementbetween the upper and lower housings (20, 40), the valve element (60)disengages from the valve seat (31), allowing fluid to flow through thevalve under conditions wherein the pressure differential between theinlet and outlet sides of the valve element is less than the valve'scracking pressure. Preferably, although not essentially, under suchconditions, even though the valve element (60) disengages from the valveseat (31), the sealing flange (54) of the lower housing continues to bein sealing contact with the upper housing's seal (30).

In a variation on this example, the upper and lower housings can bemodified to include one or more structural features that signal to auser that the valving function of the valve has been relieved (i.e., thevalve element has been disengaged from the valve seat to permit fluidflow even if the pressure differential across the valve element is lessthan the valve's rated cracking pressure) prevents the housings frombeing unscrewed, for example, more than necessary. For instance, thevalve body may be designed so that under normal use, i.e., the valve isclosed unless its rated cracking pressure is exceeded, the peripheralupper edge of the axially extending wall flange (22) extendssufficiently above the outer surface of the bottom surface flange (41)so as to create a lip or edge effect that can easily be tactily sensedby a user's finger. In contrast, when the upper and lower housings havebeen sufficiently moved to provide relief of valve function, the lip oredge effect can no longer be felt.

In another variation, the upper and lower housings have structuralfeatures that prevent relative movement beyond more than a predeterminedamount.

In still another variation, rotation of one housing in relation to theother housing results in a visible change that can be observed by theuser. For example, a window in one housing may expose one of two or moredifferent colors or symbols to be visible in the window to signalwhether the valve is the closed (i.e., fluid flow checking position) oropen ((i.e., flow checking function relieved) position. Colored panelssuch as red and green, “−” and “+”, or the like may be used to indicatewhether the valve's check function is operation or not, respectively.

B. Relievable Check Valves Using A Non-Flow Pressure Differential

Another aspect of the invention concerns relievable one-way check valveswherein a pressure other than fluid pressure is used to create asufficient pressure differential across the valve element to cause thevalve to open and permit fluid flow. Any suitable structure, orcombination of structures, that provides such disengagement of the valveelement from the valve seat is within the scope of the invention. Arepresentative example involves the use magnetic repulsion. Anotherexemplary configuration allows movement of a mechanical supportstructure for the valve element in relation to the lower housing, whichmovement disengages the valve element from the valve seat.

C. Relievable Check Valves Having A Fluid Bypass

Yet another aspect of the invention concerns relievable one-way checkvalves having a secondary fluid flow path that allows the primary fluidpath, which contains a check valve, to be bypassed when desired.

All of the articles and methods described and claimed herein can be madeand executed without undue experimentation in light of the presentspecification. While the articles and methods of this invention havebeen described in terms of preferred embodiments, it will be apparent tothose of skill in the art that variations may be applied to the articlesand methods. All such similar substitutes and modifications apparent tothose skilled in the art are deemed to be within the spirit and scope ofthe invention as defined by the appended claims.

All patents, patent applications, and publications mentioned in thespecification are indicative of the levels of those of ordinary skill inthe art to which the invention pertains. All patents, patentapplications, and publications, including those to which priority oranother benefit is claimed, are herein incorporated by reference to thesame extent as if each individual publication was specifically andindividually indicated to be incorporated by reference.

The invention illustratively described herein suitably may be practicedin the absence of any element(s) not specifically disclosed herein.Thus, for example, in each instance herein any of the terms“comprising”, “consisting essentially of”, and “consisting of” may bereplaced with either of the other two terms. The terms and expressionswhich have been employed are used as terms of description and not oflimitation, and there is no intention that in the use of such terms andexpressions of excluding any equivalents of the features shown anddescribed or portions thereof, but it is recognized that variousmodifications are possible within the scope of the invention claimed.Thus, it should be understood that although the present invention hasbeen specifically disclosed by preferred embodiments and optionalfeatures, modification and variation of the concepts herein disclosedmay be resorted to by those skilled in the art, and that suchmodifications and variations are considered to be within the scope ofthis invention as defined by the appended claims.

1. A relievable one-way check valve, comprising: (a) a valve housinghaving a valve seat; (b) a valve element within the valve housing thatis biased against the valve seat in a normally closed position but thatopens when exposed to a pressure differential that meets or exceeds arated cracking pressure for the valve; and (c) a valve relief featurethat, when actuated a user, opens the valve to fluid flow at a pressurethat is less than a rated cracking pressure for the valve.
 2. A valveaccording to claim 1, wherein the valve relief feature, when actuated,causes change in a physical relationship between the valve seat andvalve element, resulting in fluid flow through the valve even if thepressure differential across the valve element is less than the ratedcracking pressure for the valve.
 3. A valve according to claim 1,wherein the valve relief feature, when actuated, causes application of apressure other than fluid pressure to create a sufficient pressuredifferential between the inlet and outlet sides of the valve element tocause the valve to open and permit fluid flow.
 4. A valve according toclaim 1, wherein the valve relief feature, when actuated, provides asecond flow through the valve that avoids the valve element.